This speech bandpass filter circuit appears in the TI OPA344 datasheet. It says "G = 100" and passband is 300 Hz to 3 kHz. How is the gain and corner frequencies calculated from the various component values? I'd like to try this circuit but I only need a gain of 5 and I might want to tweak the passband.
I think I see that R7 and C2 form a first order low pass filter with a corner frequency of 3120 Hz. And I believe R6 and R5 produce a gain of (1 + R6/R5) = 6. But I don't understand the rest of the circuit. Where is the rest of the gain and the high pass filter?